Curtain wall construction



May 5, 1970 M. V. BROOKS CURTAIN WALL CONSTRUCTION Filed Dec. 21, 1967 ,lo u I 4 Sheets-Sheet 1 a r 2}? L INVENTOR AJHRVW V. 5/?0016' BY W M ATTORNEY y 5, 1970 M. v. BROOKS 3,509,672

CURTAIN WALL CONSTRUCTION Filed Dec. 21, 196'? 4 Sheets-Sheet 2 FIG- 3 INVENTOR MARVIN v. fimoxs BY CUJ QM ATTORNEYS May 5, 970 M. v. BROOKS 3,509,672

CURTAIN WALL CONSTRUCTION Filed Dec. 21. 1967 4 Sheets-Sheet 4.

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INVENTOR MAR VIN V. BROOK-5' ATTORNEYS United States Patent M 3,509,672 CURTAIN WALL CONSTRUCTION Marvin V. Brooks, Kokomo, Ind., assignor to PPG Industries, Inc., a corporation of Pennsylvania Filed Dec. 21, 1967, Ser. No. 692,440 Int. Cl. E0413 1/70, 2/88 US. Cl. 52-235 6 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to a wall construction and, in particular, to a novel, insulated curtain wall construction.

In US. Pat. No. 3,336,707, assigned to the assignee of the present invention, there is disclosed an insulated curtain wall construction for mounting panels on a frame or grid structure comprising a T-shaped elastomeric structural glazing gasket having a body or arm portion of the gasket in supporting engagement with a panel, the leg portion of the gasket received in an inwardly directed mounting groove in a frame member and gasket engagement means supported within said groove and engaging the leg portion of the gasket to lock the assembly together.

In copending application Ser. No. 596,285, also assigned to the assignee of the present invention, there is disclosed an insulated wall construction for mounting panels comprising horizontal and vertical members interconnected to form a frame and wherein each frame member carries an outwardly directed flange on one common vertical face thereof, an elastomeric structural glazing gasket mounted on said flange to support a panel and insulating panel-backing strips disposed between said panel and said frame member. To the present inventors knowledge, the above constructions represent the only fully insulated curtain wall systems of their kind.

In known forms of wall construction prior to the above inventions, various attempts were made to provide a thermal grid barrier, i.e., a thermal break in the grid or frame members, as well as thermal break between the panel members and the grid or frame members, to prevent any undesired transfer of heat and cold from one member to another. However, none of these known forms of construction were found to be completely satisfactory.

Even with the advent of the above-mentioned inventions wherein for the first time completely satisfactory constructions were provided for producing both structurally and functionally sound thermal wall systems, these systems were nevertheless restricted in appearance and required maintaining close tolerances in the manufacture of their component parts. Each of the foregoing systems required the use of an exposed elastomeric glazing gasket, the appearance of which in a composite Wall assembly might not always completely fulfill the aesthetic desires of the architect and/or building owner. Moreover, both of the above-mentioned systems might well be characterized as non-adjustable systems in that they contained no 3,509,672 Patented May 5, 1970 provision for field adjustment of components in order to positively obtain a water-tight and/or structurally-tight wall. Accordingly, each of these systems required maintaining strict control over field erection and tolerance deviations in the manufacture of their component elements or parts.

The present invention is directed to providing a solution to the above-mentioned problems and, more specifically, to providing a thermally insulated, metal-faced, panel-framing structure that is not hampered by tolerance considerations and that may be adapted to provide almost any desired appearance.

The present invention, like those disclosed in the aforementioned patent and copending application, combines all of the best features of known types or forms of curtain wall construction and provides a novel curtain wall system that is structurally sound, that is relatively easy and inexpensive to install, that provides an efficient thermal grid barrier, and that is comparable or lower in cost to any known form of wall construction.

In addition, the curtain wall system of the present invention, unlike those disclosed in the aforementioned patent and copending application, is adjustable to accommodate tolerance deviations and, accordingly, is not inherently or unduly hampered by tolerance considerations. Also, the curtain wall system of this invention permits wide versatility in the finish, color, shape and/or appearance of depth of section of the panel-framing members by reason of employing panel-framing and/or cap or cover members that can be fabricated to provide practically any desired appearance.

Moreover, the curtain wall system of this invention can accommodate mounting panels either from the interior or the exterior of the building for maximum economy in initial panel installation and subsequent panel replacement.

Furthermore, the curtain wall system of this invention is provided with an efficient weep system that includes the use of a pressure-equalizing baffling member to assure that water produced by condensation or rain is always released to the exterior side of the wall structure. In addition, the present curtain wall system is provided with a novel anchor and glazing stop construction that provides maximum desired support for the metal framing system, as well as maximum support for the panel members framed and retained therewithin.

The foregoing and other features and advantages of this invention will be better understood when reference is had to the accompanying drawings, wherein similar parts are usually designated by the same numeral and in which:

FIG. 1 represents an outside elevation of a typical curtain wall constructed in accordance with the present invention;

FIG. 2 is a schematic representation of a typical wall section along the line IIII of FIG. 1;

FIG. 3 is a typical cross-section along the line IIIIII of FIG. 1 showing the details of vertical framing members constructed in accordance with the present invention;

FIG. 4 is a typical cross-section along the line IVIV of FIG. 1 showing the details of horizontal framing members constructed in accordance with the present invention;

FIG. 5 is a side elevation of the preferred anchor structure and glazing stop for the vertical mullions of this invention;

FIG. 6 is a typical cross-section along the line VIVI of FIG. 5 showing further details of the preferred anchor structure and glazing stop of this invention; and

FIG. 7 is a back view of a horizontal expansion joint with certain parts removed for the sake of clarity.

The curtain wall 10 depicted in FIG. 1 consists of a plurality of panels 11 which are separated and supported along their peripheral edges by horizontal and vertical panel-framing members or grid members 12 and 13. Although FIG. 1 is intended to show horizontal and vertical framing members supporting a plurality of panels covering a complete wall section, it will be appreciated from the following description that the present invention is equally well adapted to singleor multiple-panel constructions. The panels 11 may be of an insulating or non-insulating type and of any suitable material or construction.

' Referring to FIG. 2, one of a plurality of vertical framing members 13 is shown afiixed to the outside of a building structure by means of anchors 14. Horizontal framing members 12, as shown, are joined to the vertical framing members 13 to form a rigid structural frame or framework. With particular reference being had to FIGS. 3 and 4, the horizontal and vertical framing members 12 and 13 are each composed essentially of a metal clamp member or panel-retaining member 15 and a metal mullion or panel-facing member 16 joined in assembled relation by bolts 17 and nuts 18 so that the panel-retaining member and panel-facing member are thermally insulated from each other by relatively low thermal conductivity material. In the embodiment shown, this thermally insulated connection is accomplished by the use of insulating spacer material at each bolted connection. In addition, each panel 11 is thermally insulated from at least its panelretaining members by use of insulating glazing strips or beads 19.

As best shown on the right in FIG. 3, vertical framing members 13 comprise an elongated panel-facing member 20 and an elongated panel-retaining member 21 joined at spaced intervals by means of a bolt 17 and a nut 18. Panel-facing member 20, in the embodiment shown, is an integral portion of an essentially I-shaped, structural frame member comprising a web 22 and pairs of oppositely directed flanges 23, 24 and 25, 26. However, it will be appreciated from that which follows that this I-shaped or I-beam configuration may be varied to suit the particular desires of the architect and/or building owner so long as the configuration of the panel-facing surface 27 of this member is not substantially changed and provided that the new design will satisfy the structural requirements of the wall. In other words, the vertical mullion carrying the panel-facing member may be square, rectangular, pyramidal, I-shaped, T-shaped, etc. in cross-section. Since the I-beam configuration is an eflicient one both from the standpoint of economy and effective use of metal, it has been shown.

Panel-facing member 20 carries on each of the longitudinal, marginal edges of its panel-facing surface 27 a structure adapted to support an elongated strip of glazing material, such as a glazing bead of relatively low thermal conductivity neoprene rubber or the like. For this purpose, longitudinally extending flanges 28 and 29 are provided at the marginal edges of the panel-facing surface 27 of vertical panel-facing member 20. A longitudinal groove 30 is provided in each of the flanges 28 and 29 for the purpose of receiving and retaining therein a correspondingly shaped portion of a glazing strip 19. Intermediate the glazing bead flanges 28 and 29 and at the juncture of flanges 25 and 26 with web 22 there is provided in panel-facing surface 27 a longitudinally extending groove 31 which, in the embodiment shown, has the cross-sectional shape of the head portion and proximate stern portion of a carriage bolt. Groove 31 is provided for the purpose of longitudinally receiving and retaining therein the head portion of carriage bolts 17 used to join the vertical panel-facing member 20 to the vertical panelretaining member 21. As shown in the middle in FIG. 3, the head and proximate stem portions of bolts 17 are supported within groove 31 in spaced relation to the walls or surfaces defining the groove by means of a spacer 32 provided at each bolted connection. Also, a spacer 33 is provided at each bolted connection so that panel-facing member 20 is supported in spaced relation to panel-retaining member 21. For reasons that will become more apparent hereinafter, spacers 32 and 33 are composed of a relatively low thermal conductivity insulating material,

such as a high pressure laminated insulating materiaL.

Also for reasons that will become more apparent later, flanges 23 and 24 of the vertical mullion carrying panelfacing member 20 are each provided near their free ends with an arcuate shaped groove 34 for the purpose of receiving therein an alignment pin.

As shown on the left in FIG. 3, vertical panel-retaining member 21 is an elongated channel member having a web 36, a pair of spaced flanges 37 and 38 extending rearwardly from the opposite longitudinal marginal edges of the web 36 and a further pair of spaced flanges 39 and 40 extending forwardly from a longitudinal central portion of the wab 36. Rearwardly extending flanges 37 and 38 are provided with a structure adapted to engage and support an interior snap-on cover member 41, as shown on the right in FIG. 3. Opposite each of the flanges 37 and 38 on the panel-retaining surface 42 of web 36', there is provided a structure adapted to support an elongated glazing strip or bead 19. Each of these glazing bead supporting structures includes a groove 43 for the purpose of receiving and retaining therein a correspondingly shaped portion of the glazing bead. As mentioned above, the glazing bead is composed of a relatively low thermal conductivity meterial, such as neopreme rubber. Forwardly extending flanges 39 and 40 project from the panel-re taining surface 42 of web 36 and are located on opposite sides of, and in spaced relation to, the threaded stems of the bolts 17 extending from the panel-facing member 20. The free ends of flanges 39 and 40' abut against one side of spacer 33, the opposite side of which abuts against the panel-facing surface 27 of panel-facing member 20-. Spaced apertures, not shown, are provided in the web 36 of panel-retaining member 21 for the purpose of receiving the threaded end of the stern of carriage bolts 17. A- spacer or washer 44 is provided under the nuts 18 threadably received on bolts 17, and these washers are preferably also composed of a relatively low thermal conductivity insulating material.

As best shown at the top in FIG. 4, horizontal framing members 12 comprise an elongated panel-facing member 45 and an elongated panel-retaining member 46 joined at spaced intervals by means of a bolt 17 and a nut 18. Panel-facing member 45 is an integral portion of an essentially T -shaped structural frame member or horizontal mullion. Oppositely directed flanges 47 and 48 that form the arms of this T-shaped member have formed on their free ends a longitudinally extending grooved flange 49 adapted to support an aiongated strip of glazing material 19 against panels 11. Flange 48, as shown, is longitudinally split into two parts, which are pointed together by means of a plurality of spaced screws 50 extending through part 51 and threadably received in a longitudinally extending angle flange 52 integrally formed on part 53. Removal of part 53 facilitates the installation and replacement of panels from the exterior of the building, if desired. Flange 54, that forms the leg of this T-shaped member, extends rearwardly of panels 11 and has integrally formed on its free end a pair of divergent flanges 55 and 56.

As shown at the middle in FIG. 4, angle flanges 57 and 58 are integrally formed on the free ends of flanges 55 and 56, respectively, with the free ends of flanges 57 and 58, in turn, being disposed in converging, opposed relationship to thereby form a longitudinally extending groove 59 having a restricted opening. Groove 59, as was the case with groove 31 in the vertical panel-framing member, has the crosssectional shape of the head portion and proximate stem portion of a carriage bolt. Likewise, groove 59 is provided for the purpose of longitudinally receiving and retaining therein the head portion of carriage bolts 17 used to join the horizontal panel-facing member 45 to the horizontal panel-retaining member 46. The head and proximate stem portions of bolts 17 are supported in groove 59 in spaced relation to the walls or surfaces defining the groove by means of a spacer 60 provided at each bolted connection. Also, a spacer 61 is provided at each bolted connection so that panel-facing member is supported in spaced relation to panel-retaining member 46. Spacers and 61 are composed of a relatively low thermal conductivity insulating material, such as a high pressure laminated insulating material.

Horizontal panel-retaining member 46 is an elongated channel-shaped member having a web 62 and a pair of spaced flanges 63 and 64 extending forwardly thereof from the opposite longitudinal marginal edges of the web 62. Forwardly extending flanges 63 and 64 carry on their free end a structure adapted to support an elongated glazing strip or bead 19. Each of these glazing bead supporting structures includes a groove 65 for the purpose of receiving and retaining therein a correspondingly shaped portion of the glazing head, which is composed of a relatively low thermal conductivity material, such as neoprene rubber. As shown in FIG. 4, web 62 abuts against one side of spacer 61, the opposite side of which abuts against angle flanges 57 and 58 that define a portion of groove 59 in the horizontal panel-facing member 45. Spaced apertures, not shown, are provided in the web 62 of panel-retaining member 46 for the purpose of receiving the threaded end of the stern of carriage bolts 17. A spacer or washer 66 is provided under the nuts 18 threadably received on bolts 17 and these washers are preferably also composed of a relatively low thermal conductivity material.

As best shown at the bottom in FIG. 4, the weep system provided in conjunction with the present invention comprises a plurality of spaced apertures 67 in flange 63 of horizontal panel-retaining member 46, a darn member 68 supported on flange 63 at each end of horizontal panelretaining member 46, a plurality of apertures 69 staggered relative to apertures 67 in flange 47 of horizontal panel-facing member 45, a dam member 70 supported on flange 54 at each end of horizontal panel-facing member 45, and a pressure-equalizing baflling member or cover member 71. As will be apparent from FIG. 4, moisture that condenses on the back surface of panels 11 will drop onto the upper surface of flange 63. Flange 63, as shown, may be formed in various ways, including the provision thereon of one or more additional flanges, such as flange 72, to provide a recess or gutter 73 for the moisture received on its upper surface. Any collection of moisture that occurs therein passes through apertures 67 onto the upper surface of gutter flange 54, then through apertures 69 into a space provided between baflling member 71 and panel-facing member 45 and outwardly through an elongated slot extending essentially the full length of horizontal member 12.

Baflling member 71 is an elongated channel member having a web 35 laterally spaced from the flanges 47 and 48 of panel-facing member 45, and a pair of flanges 74 and 75 secured to the free ends of flanges 47 and 48. Flange 74 is secured to the free end of flange 47 by means of a tongue and groove snap-on structure 76 provided therebetween. Flange 75 is secured to the free end of flange 48 by means of screws 77 in a manner that provides essentially a continuous slot or space between flange 75 and the free end of flange 48. In the embodiment shown, this is accomplished by flange 75 being spaced from the free end of flange 48 for essentially their entire length, with the only physical connection between these two elements occurring where screws 77 are inserted therebetween for the purpose of attachment. Generally, a screw at each vertical member is all that is required for this purpose. A small spacer, or the like, such as a short, e.g., one-half inch to one inch long, L-shaped flange 78 integrally formed on the free end of flange 48 is preferably provided at each screw attachment to assure the desir d spacing of flange 75 from flange 48 and to facilitate attachment of baflling member 71 thereto and to panelfacing member 45.

By reason of baflling member 71 being constructed and arranged to provide an essentially continuous open slot communicating with space 79 and located along the exposed lower surface of horizontal member 12, it is virtually impossible to drive moisture either into or backward through the weep system and thence into the interior side of the wall structure. Even under the most severe conditions of high,dynamic windloading, coupled with heavy rain, the open, lower side of the baffling member 71 precludes water from collecting or being retained within space 79 between baflling member 71 and panel-facing member 45. Furthermore, this open construction has a pressure-equalizing or pressure-moderating effect on the air within space 79 when the wall is exposed to dynamic windloading. In known forms of construction that provide only spaced apertures for limited egress of water from space 79 and that otherwise essentially enclose space 79, it is possible, under dynamic windloading, to build up a sufficient pressure within space 79 to drive water backward through the weep system. As will be apparent, the present baffling or cover member 71, by reason of its open construction, precludes supporting a build-up of pressure within space 79 such that water could be forced backward through the weep system.

Turning to FIGS. 5 and 6, there is shown the preferred anchor structure for the vertical mullions of this invention. As shown, anchor 14 comprises a vertically arranged plate or tongue member 80 having its sides clamped between a pair of vertically disposed angle brackets 81 and its forwardly projecting edge 82 received in interlocking engagement with vertical panel-facing member 20. Angle brackets 81 each have a first flange 83 rigidly secured to the outside of a building slab 84 by suitable fastening means 85 and a second flange 86 extending normal to building slab 84. Flanges 86 are in spaced, opposed relation to each other and receive therebetween opposite side portions of tongue member 80. Disposed between each of the opposite sides of tongue member 80 and the adjacent flange 86 of bracket 81 is a separator 87 composed of a relatively low thermal conductivity insulating material, such as a high pressure laminated insulating material. Bolts 88 are received in aligned apertures drilled through flanges 86, separators 87 and tongue member 80 for the purpose of securing these members in assembled relation.

The forward edge of tongue member 80, as well as the top and bottom edges thereof, project beyond the corresponding edges of flanges 86. The forward edge of tongue member 80 has formed thereon a structure corresponding generally in size and shape to that of groove 31 in vertical panel-facing member 20. This edge structure is longitudinally received in interlocking engagement in groove 31 of panel-facing member 20. Also longitudinally received in interlocking engagement with panel-facing member 20 are elongated flanges 89 and 90 that extent laterally outwardly from each side of tongue member 80. Flanges 89 and 90 have a forward surface that corresponds generally in shape to the adjacent panel-facing surface portion of panel-facing member 20. The free end of flanges 89 and 90 is provided with a tongue portion 91 that interlocks with a groove 92 provided on glazing flanges 28 and 29 of panel-facing member 20.

Rearwardly of flanges 89 and 90, and extending laterally outwardly from each side of tongue member 80, are elongated flanges 93- and 94. Flanges 93 and 94 provide partial support for glazing stops 95. Glazing stops 95 provide glazing support for panels 11, Where otherwise support would either be removed or substantially weakened by reason of removing a suflicient portion of panelretaining member 21 to permit tongue member 80 to pass therethrough and interlock with panel-facing member 20.

As shown in FIGS. 5 and 6, panel-retaining member 21 terminates slightly short of the top and bottom edges of tongue member 80. A glazing stop 95 is provided at each anchorage on both sides of tongue member 80. Glazing stop 95 is an elongated, vertical member that is essentially coextensive in length with tongue member 80. Glazing stop 95 has a first flange 96 disposed parallel to tongue member 80 and a second flange 97 located intermediate the vertical edges of the first flange 96 and extending in supporting relation toward an adjacent panel 11 or a suitable substitute therefor. Flange 96 is secured at its rear edge to the exposed top and bottom. portions of tongue member 80 by means of scr ws 98 and spacing shims 99. Flange 96 is supported at its front edge on flange 93 or 94. As shown, the front edge of flange 96 and the free end of flanges 93 and 94 are provided with an interlocking tongue and groove structure that resists lat eral displacement of the adjacent longitudinal portions of these flanges when flange 96 is bolted to tongue member 80. Glazing flange 97 has formed on its free end a structure adapted to support an elongated strip of insulating glazing material.

As shown in FIG. 5, a pair of alignment pins 130 extend between the ends of each adjacent length of a vertical panel-facing member. Each alignment 101] is fixed in a groove 34 in one vertical mullion and slidably received in a corresponding groove 34 in the adjacent vertical mullion. The alignment pins maintain these members in vertical alignment during expansion and contraction. Expansion and contraction ofthe vertical members is further accommodated in the disclosed construction by providing or maintaining a slip connection between tongue member 80 and vertical panel-facing member 20 at each vertical expansion joint. In the embodiment shown, for example, it is contemplated that a vertical member will be continuous in length for a span of two floors. Accordingly, an expansion joint would occur at the end of each length of vertical mullion or at every other floor, with a fixed connection or anchorage occurring at the intermediate floor. It will be understood that FIG. 5 and 6 represent a typical anchorage at a slip connection and that anchorage at a fixed connection is similar, except that there will be no vertical expansion joint and the anchored tongue is rigidly fastened to the structural mullion or panel-facing member 2i), as by means of welding.

FIG. 7 shows a back view of a horizontal expansion joint with all panels, glazing beads, panel-retaining members and interior cover members removed for the sake of clarity. A hanger clip 101 and a support clip 102 are each attached to vertical panel-facing member 20 by means of a carriage bolt received in groove 31 and a nut 18 secured thereon. Hanger clip 101 is provided with a flange 103 at its lower edge that is received in the upper grooved flange 49 provided on each of the adjacent horizontal panel-facing members for the purpose of supporting a glazing bead. Support clip 162 has its upper flange 104 in underlying supporting engagement with the flange 54 provided on each of the adjacent horizontal panelfacing members. It will also be apparent, by reference to (FIG. 7 and FIG. 3, that the vertical glazing legs or flanges 28 and 29 are notched at each intersection to clear the horizontal panel-facing member 45 that passes therebehind. It will be understood that the joint shown in FIG. 7 represents a typical horizontal expansion joint and that other joints are similar, except that the horizontal member is continuous and water dams are omitted.

It will be appreciated that, among other novel features, the construction of this invention provides a novel metalfaced, insulated curtain wall system that is fully adjustable to accommodate any deviations either in building tolerances or in the tolerances specified for the manufacture of its component elements or parts. Also, the curtain Wall system of this invention is provided with an eflicient weep system that includes the use of pressure-equalizing bafliing members or cover members to assure that water produced by condensation or rain is always released to the exterior side of the Wall structure. In addition, the present curtain Wall system is provided with a novel anchor and glazing stop construction that provides maximum desired support for the metal framing system, as well as maximum support for the panel members framed and retained therewithin.

What is claimed is:

1. An insulated curtain wall construction comprising horizontal and vertical structural stiflening members interconnected to form a frame, with each frame member carrying a anel-facing member, a panel with an edge disposed between said panel-facing member and a panel-retaining member, connector means joining said panel-facing member to said panel-retaining member, and insulating material disposed between said connector means and said panelfacing member so that said panel-retaining member and panel-facing member are insulated from each other,

an anchor member aflixed to a vertical panel-facing member and the outside of a building, said anchor member comprising a vertically arranged plate joined by fastening means to a bracket affixed to said out side of said building, the forwardly projecting edge of said plate being received in interlocking engagement with said vertical panel-facing member, a separator composed of relatively low thermal conductivity insulating material disposed between said plate and adjacent portions of said bracket, and the vertical panel-retaining member being terminated slightly short of the top and bottom edges of said vertically arranged anchor plate,

a glazing stop that is essentially coextensive in length with said anchor plate fastened to at least one side of said anchor plate, said glazing stop having means formed thereon that coacts with a portion of said anchor plate to resist lateral displacement of said glazing stop relative to said anchor plate and additional means formed thereon for supporting an elongated glazing strip in contact with said panel.

2. An insulated curtain wall construction according to claim 1 wherein at least one horizontal panel-facing member has a gutter flange and means of egress from said gutter flange to the exterior side of said one horizontal panel-facing member for the purpose of weeping moisture and condensation from between said panel-facing and panel-retaining members.

3. A wall construction comprising a vertical panel-facing member joined to a vertical panel-retaining member with an edge of a panel disposed therebetween, an anchor member aflixed to said vertical panel-facing member and the outside of a building, said vertical panel-retaining member being terminated slightly short of said anchor member, said anchor member comprising a vertically disposed plate joined by fastening means to a bracket aflixed to the outside of said building, a separator composed of relatively low thermal conductivity material disposed between said plate and adjacent portions of said bracket and a glazing stop fastened to said anchor member in supporting relation with adjacent edge portions of said panel.

4. The wall construction of claim 3 which further includes a horizontal panel-facing member joined to a horizontal panel-retaining member with an edge of said panel disposed therebetween, said horizontal panel-facing member being an elongated member provided with weep openings and having means formed on opposite longitu dinal edge portions thereof to support a cover member, and a cover member aflixed to said cover member supporting means with portions of said cover member being spaced from adjacent portions of the lower longitudinal edge of said horizontal panel-facing member so that'an elongated slot extending substantially the full length of said horizontal panel-facing member is provided between said cover member and said horizontal panel-facing member.

5. The wall construction of claim 3 Which further includes a horizontal panel-facing member joined to a horizontal panel-retaining member with an edge of said panel disposed therebetween, said horizontal panel-facing member being longitudinally split into two parts comprising a first part joined to said horizontal panel-retaining member and a second part disposed in supporting relation with the above-mentioned edge of said panel, said second part being secured by removable fastening means to said first part so that said fastening means are removable from the exterior side of said wall when said panel is in its installed position.

6. The wall construction of claim 3 wherein said panelfacing members and panel-retaining members are joined by connector means, and relatively low thermal conductivity material is disposed between said connector means and said panel-facing members so that said panel-facing members and panel-retaining members are insulated from each other.

References Cited UNITED STATES PATENTS 6/ 1924 Kusterle 52-499 8/ 1960 Ferrell 52-235 3/1961 Toney 52-463 X 9/1962 Hammitt et al 52-464 X 9/1964' Horgan 52-303 X 9/1965 Bakke 52-235 2/1968 Johnston 52-395 X FOREIGN PATENTS 7/ 1964 Australia. 4/ 1958 France.

US. Cl. X.R. 

